In which case would facilitated diffusion be needed? A. With very small non polar particles moving down the concentration gradient. B. With very small polar particles moving against the concentration gradient. C. With large polar molecules moving against the concentration gradient. D. With large non polar molecules moving down the concentration gradient.

All the organisms living in and around the streambed, together with the rocks, substrate, water, surrounding air, and other non-living components

Explanation:

An ecosystem is interaction between living and nonliving things in an area. There are biotic and abiotic factor, abiotic means non living things such as air and biotic means living things such as animals.